This research project is intended to exploit extensively the cerebellum as a model for developmental neuromorphology and synaptogenesis. Short, pilot investigations of other neural systems are included to provide confirmation of events observed in the cerebellum and thought to have general significance, as well as to shed light on the development of special synaptic devices, not present in the cerebellum. The work proposed for the coming year involves: 1) Continuing studies on the turtle cerebellum; 2) Experimental neuroanatomical studies on the cat cerebellum; 3) Studies on the development and distribution of "gap junctions" in the cerebellum of the chick in sectioned and freeze-fractured materials; 4) Freeze-fractured membranes of axons in the turtle and chick cerebella; 5) (a) Fine structure of the ciliary ganglion in the chick; (b) Development of the chick ciliary ganglion; 6) Quantitative analysas on the synapses between basket cell axons and dendritic spines of Purkinje cells in the chick cerebellar cortex; and 7) A pilot study on the identification of aminergic terminals in the cerebellum.